This is a long-range project designed to improve epidemiologic methods for studying reproductive outcomes, particularly for studying spontaneous abortion, and to investigate the association between environmental exposures and reproductive outcomes. There are several facets to this project. A comprehensive reproductive questionnaire has been developed, and a study has been designed to test the validity of questionnaire data. The basic epidemiology of spontaneous abortion is being investigated using an extensive, previously-unanalyzed data set. Possible confounders in epidemiologic studies of spontaneous abortion are being analyzed, and questions regarding the underlying biological mechanisms of spontaneous abortion are being examined. Finally, a study of reproductive outcomes among workers exposed to perchloroethylene is being prepared. This solvent is widely used in drycleaning and has been shown in the laboratory to be a mutagen and carcinogen.